The present invention relates to a guidance system for guiding an unmanned vehicle which automatically transports goods in an office or a factory.
Recently, a system for transporting documents, goods, component parts, and so on by an unmanned vehicle along a predetermined course in an office or a factory has been put into practical use. Various types of guidance systems are proposed for guiding the unmanned vehicle to a target position correctly within a minimum time. Some of such guidance systems are practically used. A guidance system of this type consists of, in principle, guide lanes arranged on a predetermined course and comprising a light-reflecting plate, a metal plate, a magnetic plate or the like, markers for notifying the position of the vehicle, sensors, such as photoelectric sensors, metal sensors, or magnetic sensors, for detecting a positional deviation with respect to the corresponding markers, an auto drive system for driving the unmanned vehicle by output signals from the sensors, and so on.
In the conventional guidance system of the unmanned vehicle, the following problems are posed. First, guide lanes and markers are provided in, e.g., a factory for a specific course connecting stations which are provided in accordance with the arrangement of the workers and machines. Therefore, when the number or positions of the stations are frequently changed due to the increase in the number of the machines and changes in the positions of the machines, as in recent factories, the guide lanes and markers must be rearranged accordingly, resulting in cumbersome and uneconomical procedures.
In order to prevent deviation from the guide lane, the vehicle usually detects the direction and magnitude of deviation of the unmanned vehicle from the guide lane in accordance with a difference signal between the outputs of two sensors (guide sensors). With this method, when the vehicle is at an intersection or branching point of guide lanes, an output corresponding to the positional deviation of the vehicle cannot be obtained from the difference signal between the outputs of the two guide sensors. Therefore, a marker must be provided in the vicinity of each branching or intersection point, and a marker sensor must be provided to the unmanned vehicle in addition to the guide sensors. With this method, when the number of the branching or intersection points of the guide lanes is increased, a required number of markers is greatly increased, and the cost of the markers shares a considerably large proportion of the cost required for installation of the unmanned vehicle guidance system.